This invention relates in general to a flat-panel display and in particular to an improved structure for a full color, high resolution capable flat-panel display which operates at a high efficiency.
A flat-panel display is an electronic display in which a large orthogonal array of display pixels, such as electro-luminescent devices, AC plasma panels, DC plasma panels and field emission displays and the like form a flat screen.
The basic structure of an AC Plasma Display Panel, or PDP, comprises two glass plates with a conductor pattern of electrodes on the inner surfaces of each plate. The plates are separated by a gas filled gap. The electrodes are configured in an x-y matrix with the electrodes on each plate deposited at right angles to each other using conventional thin or thick film techniques. At least one set of sustaining electrodes of the AC PDP is covered with a thin glass dielectric layer. The glass plates are assembled into a sandwich with the gap between the plates fixed by spacers. The edges of the plates are sealed and the cavity between the plates is evacuated and filled with a mixture of neon and xenon gases or a similar gas mixture of a type well known in the art.
During operation of an AC PDP, a sufficient driver voltage pulse is applied to the electrodes to ionize the gas contained between the plates. When the gas ionizes, the dielectrics charge like small capacitors, which reduces the voltage across the gas and extinguishes the discharge. The capacitive voltages are due to stored charge and are conventionally called wall charge. The voltage is then reversed, and the sum of the driver voltage and wall charge voltages is again large enough to excite the gas and produce a glow discharge pulse. A sequence of such driver voltages repetitively applied is called the sustaining voltage, or sustainer. With the sustainer waveform, pixels which have had charge stored will discharge and emit light pulses at every sustainer cycle. Pixels which have no charge stored will not emit light. As appropriate waveforms are applied across the x-y matrix of electrodes, small light emitting pixels form a visual picture.
Typically, layers of red, green or blue phosphor are alternately deposited upon the inner surface of one of the plates. The ionized gas causes the phosphor to emit a colored light from each pixel. Barrier ribs are typically disposed between the plates to prevent cross-color and cross-pixel interference between the electrodes. The barrier ribs also increase the resolution to provide a sharply defined picture. The barrier ribs further provide a uniform discharge space between the glass plates by utilizing the barrier rib height, width and pattern gap to achieve a desired pixel pitch.
Further details of the structure and operation of an AC PDP are disclosed in U.S. Pat. No. 5,723,945 titled xe2x80x9cFLAT PANEL DISPLAYxe2x80x9d; U.S. Pat. No. 5,962,983, entitled xe2x80x9cMETHOD OF OPERATION OF DISPLAY PANELxe2x80x9d; and U.S. patent application Ser. No. 09/259,940, filed Mar. 1, 1999, entitled xe2x80x9cFLAT-PANEL DISPLAYxe2x80x9d, all of which are incorporated herein by reference.
This invention relates to an improved plasma flat-panel display which includes at least one auxiliary electrode disposed between each pair of sustaining electrodes.
It is known to manufacture plasma flat-panel displays having pairs of sustaining electrodes which establish a charged volume between the display substrates. The charge is controlled by applying voltages to a plurality of address electrodes. The charged volume is established by applying a voltage to the sustaining electrodes. The efficiency of the panel is generally greater when gas and geometry parameters are adjusted to increase the voltage required to sustain a discharge. However, this is in conflict with the need to have low voltages for economic and reliability purposes. Therefore, it would be desirable to develop a compromise device which would allow initiation and control of the sustaining discharge with a less powerful and lower voltage controlling means.
The present invention contemplates a plasma flat-panel display having a first transparent substrate with at least one pair of parallel sustaining electrodes deposited thereupon. A least one auxiliary electrode is deposited upon the first substrate parallel to the sustaining electrodes. The panel also includes an charge storage surface coating which covers the sustaining and auxiliary electrode.
The panel further includes a second substrate which is hermetically sealed to the first substrate, the second substrate having a plurality of gas-filled micro-voids formed in a surface thereof which is adjacent to the first substrate. The micro-voids are generally perpendicular to the sustaining and auxiliary electrodes and cooperate with the first substrate to define a plurality of sub-pixels. A plurality of address electrodes are incorporated within the second substrate, each of the address electrodes corresponding to one of the sub-pixels.
A first voltage is applied to the auxiliary electrode of sufficient magnitude to inject a charge of electrons between the auxiliary electrode and an associated sustaining electrode and initiate a discharge therebetween. A second voltage, that is greater than the first voltage is applied to the sustaining electrodes to extend the discharge to the other sustaining electrode. The voltage applied to the auxiliary electrode can be changed to urge the discharge deeper into the associated micro-void. In the preferred embodiment, the first voltage is applied before the second voltage; however, the invention also can be practiced with the first and second voltages being applied simultaneously or with the second voltage applied before the first voltage. The discharge between the sustaining electrodes can be controlled by applying a third voltage to the address electrodes.
It is further contemplated that a phosphor material is deposited within each micro-void and associated with the address electrodes. In the preferred embodiment, the first and second substrates are formed from glass. Additionally, the invention can be practiced having a pair of auxiliary electrodes disposed between the sustaining electrodes.
The plasma flat-panel also can include a plurality of pairs of sustaining electrodes, each pair of sustaining electrodes having at least one auxiliary electrode associated therewith. The micro-voids in the second substrate cooperate with the first substrate to define a plurality of sub-pixels which form rows parallel to the sustaining and auxiliary electrodes and columns which are perpendicular to the sustaining and auxiliary electrodes with each of the plurality of address electrodes incorporated within the second substrate corresponding to one column of the sub-pixels.
The invention further contemplates that the charge storage surface is covered by a thin film of electron emissive material. The electron emissive film may be optionally formed in a pattern from materials having differing electron emissive characteristics, for ease of generating secondary emission electrons. The ease of generating secondary emissive electrons for a material is referred to as the xe2x80x9cgammaxe2x80x9d of the material.